Kon is renowned for his superb editing and wildly creative visuals in Paprika, but for what purpose? What remains when the visuals is eliminated from the equation? Paprika's tale had a painfully obvious twist near the conclusion, and its basic outline was rather shallow. Furthermore, an extraneous romantic element that was considerably less coherent than Kon's most bizarre vision. You're probably thinking, "It's all about the execution; as long as it's done well, who cares about a weak storyline?" Indeed, execution is more crucial than content, and a dull story can be made interesting by using bizarre images and inventive editing. Take Kon's earlier work, Millennium Actress, for instance.
I merely discussed the major plot; the detective's side story was, regrettably, far more intriguing. Here, the visual is used in a way that perfectly complements his tale and conflicts; it is executed similarly to Millennium Actress. When a side plot becomes more fascinating than the main narrative, though, something is off.
Characters are also pretty weak. The antagonist lacked depth and was terribly dull. I'm afraid I can't speak for the other actors in the cast. Furthermore, Atsuko's romantic evolution towards the end was so forced it was unreal. This baffled me more than any bizarre imagery Kon could conjure up, yet again. The only character in Paprika who came close to saving face was Konakawa, the investigator. He genuinely grew during the film and had a respectable amount of characterisation.